Lubricating oil composition



Patented July 4, 1944 LUBB'ICATING OIL COMPOSITION Paul B. Van Ess,Berkeley, and Ellis 8. White, Albany, Calif asslgnors to Shell Developmet Francisco mpany. San of Delaware No Drawing.

9 Claims.

. This application is a continuation-in-part of our, application SerialNo. 376,330, flied January This inventionrelates tocompounded'lubricating oils containing added ingredients which improvetheir properties in one or more important respects. It also deals withthe addition of oil-soluble addition ,agents to compounded mineral oilsto produce lubricating oils of improved anti-wear properties forinternal combus- Calif., a corporat in Application December 26, 1941,Serial No. 424,544

' rosion inhibitors. extreme pressure compounds,

tion engines.- More particularly, it deals with the addition tolubricating oils of certain oilsoluble allophanates, which compoundshave the property of modifying or reducing the hardness of carbon formedon pistons, and of preventing the baking of carbon, in piston grooves tothe point of hardness and thus preventing the sticking of piston ringswhen running internal combustion engines for long periods of time.

It is known that in modern internal combustion engines such as aviationgasoline engines, due to their high power output and their relativelyhigh operating temperatures,- or high speed Diesel engines due ,toincomplete combustion of the fuel, piston rings have a tendency tobecome stuck in the grooves and the pistons ten'd to become worn. m

The carbon deposited in internal combustion engines may be considered oftwo kinds, dependt ing on the type of oil High-viscosity index mineraloil tends to form hard carbon which may cause severescratching of partsof thepiston,

particularly top lands as well as piston rings,

etc.; while low-viscosity index oils in general form a softer carbonwhich does not scratch or scuff so badly. The presence of detergents inlubricating oils usually increases the tendency to scratch. Thus it isknown that lubricating oils containing about 25% to 5% of oil-solubledetergents, such as the salts of polyvalent metals. or of organicamines,.with detergent-forming- ,acids, may cause damage to the toplands of pistons due toscumng.- Detergent-forming acids are, forexample. naphthenic, aromatic car- .boxylic, .hydroxy aromaticcarboxylic, ,paraflln and softening hard carbon, so that well-refinedlubricating oils containing oil-soluble detergents which heretoforecaused too much scumng can be used successfully, by adding small amountsof these allophanates; Oils so compounded have the valuable combinationof properties of keeping the piston clean, retarding or preventingringsticklng. positively reducing wear, and overcoming and preventingpiston scufllng and scratching. If desired, oxidation inhibitors,coretc., may be added further to improve the desirable properties of thecompounded oils containing the above combination of addition agents.

In stating that the allophanates modify the carbon formation on thepisto we mean that th stead of the usual hard, tough, adhesive deposits,we find that the carbon formed in the presence of the allophanates is asoft, velvety, non-adherent deposit which is almost oilyin character.Such deposits are so non-adherent they may be removed by wiping with thefinger or a soft cloth, leaving a clean metal surface. No explanationcan be offered for the above-observedphenomenon. According to thisinvention, allophanates which are added to lubricating oils containing asuflicient amount of a detergent normally to cause scratching orscuffing of'the pistons, for example,

. in Caterpillar Diesel engines, possess the following formula:

X-Bl

n Cx Rs In this formula X represents oxygen or sulfur; R2 and Rs arehydrogen or hydrocarbon radicals, preferably hydrogen; R1 is a saturatedalicyclic radical having at least 12 carbon atoms.

'I'he hydrocarbon radicals R2 and Rs may contain preferably not morethan one polar neutral or basic substltuent. Suitable substituents are.for example, halogen, -CN, OH, -OR','

Normally the alicyclic radical R1 is'sufllcient to insure the necessaryoil-solubility. 1

v Preferred R1 radicals are those having at least two aliphatic rings,which may be condensed, and each portion having at least one branchedalkyl radical. Such bi-alicyclic radicals may be obtained, for example,by hydrogenation of suitable naphthalene derivatives, as for example, asecondary or tertiary alkyl naphtholjto produce the corresponding alkyldecalols; or by suitably condensing aliphatic ketones to produceunsaturated bicyclic ketones which may then be hydrogenated to thecorresponding alcohols, closely resembling the above decalols.

The amounts of our allophanates to be added to the hydrocarbon oils willvary with the type of improvement to be achieved and with the severityof the hard carbon normally formed by the 'oil. In general, theamountsrequired vary from .1% to 10%, and preferably from .5% to 5%. Onegroup of detergents which is extremely effective in preventingringstickin'gis known to comprise the salts of polyvalent metals withorganic sulfonic acids, preferably the so-called oil-soluble petroleumsulfonic acids, also known as mahogany acids. Polyvalent metals suitablefor this purpose are, particularly, Mg. Ca, Sr, Ba, Zn, Cd, Al, Sn, Pb,Bi, Cr, Mn, Co, Ni. However, these sulfonate detergents unfor unatelycause unusually-severe sending and scr hing of the pistons. We havefound that our allophanates are, therefore, particularly useful incombination with these sulfonates in that. this combination takes fulladvantage of the highly desirable detergent property of the sulfonatewithout allowing the disadvantages to make themselves felt.

Qther types of inhibitors may be. added, such as corrosion inhibitors.which are not anti-oxidants. or extreme pressure compounds which maycontain radicals comprising elements of thegroup' consisting of S, P, orC1, provided these elements are attached in such a manner that they donot readily liberate corrosive compounds such as free sulfur,'chlorine,-or phosphoric acid, under conditions'of lubrication to which crankcaseoils are usually exp'osed.- Also, mixtures of differentinhibitors areoften very useful.

In accordance with the known fact that highviscosityindex oils causemore sending of pistons than low-viscosity oils, the combination ofdetergentsand' allophanates is'particularly useful in oils of relativelyhigh viscosity, e. g., oils having 50 viscosity index or higher.

The followingexamples further illustrate the invention:

Example I An S. A. E. 30 lubricating oil having a vs'cosity index of 55,containing 2.25% of calcium petro-. leum sulfonate (produced byconverting a commercial mahogany soap to the. I calcium salt),

0.25% phenyl alpha naphthylamine and 1.0% of an allophanate of a Cu;saturated .bicyclicalcohol The presence of oxidation inhibitors inaddition to detergents and allophanates is desirable not only to protecthese additionlagents as well as the oil from rapid destruction by oxdation,

but also to prevent corrosion which may be caused by the detergent. l

For our purposes, the oxidation inhibitorsmay roughly be divided .intotwo groups: the phenolic type and the aryl amine type. Of these two. we

have found that the latter are in general more useful. Especiallyvaluable are those am nes which eontain'at least one aromatic nucleushavfing two or more condensed aromatic rings. Thus,-

preferred anti-oxidants are, for example, the naphthylamines: primary,secondary, or tertiary alkyl, aryL-or aralkyl radicals, are'attach'ed'toan aromatic nucleus or preferably to the nitrogen atom, or both, such asphenyl alpha or beta naphthylamine, tetraline naphthylamine, alphaalpha,- alpha beta.or beta beta di-naphthylamines, various phenanthryl,anthryl, orp cyl naphthylamines, xenyl; naphthylamines, benzyl phenylnaphthylamines, -di-phenyl naphthylamines, phenyl xenyl naphthylamines,di-xenyl naphthylamines; also, various phenanthryl. anthryl,-or picylphenyl amines, etc.

If desired, however,- other oxidation inhibitors We claim as ourinvention: Y 5

may be used as well. such as alkyl phenyl amines;

di-phenyl amines: or alkyl phenols, preferably containing at. least twoalkyl radicals in2, 4, or '6 positions-to the OH radicahat least twoalkyl radicals being linked to "the'aromatc' nucleus through a tertiarycarbon atom; or alpha or beta naphthols, alkylated naphthols, p'henols,or .naphthols containing ether,thio ether, etc., linkages, polyhydric'alkyl benzenes or naphthalenes, such as alkylated catechol, etc.Suitable amounts of oxidation inhibitors usually vary between about.01%to1%. f 7

(produced by the condensation. of acetone and hydrogenation) was'subjected to a'126-hour test inv a Caterpillar test engine operated at850 R. P. M. and at v16.! BrH. P. At the end of the run, the pistonrings were free, ,the piston was clean, and the top land was free ofhard carbon the metal was "not scufied. The amount of carbon deposit atthe bottom of the top ring groove was small.

Example 11 An S. A. E. 30 lubricating oil containing 9% of rapeseed mlldvoltol as a detergent, 0.1% n-butvl arsine disulflde as acorrosioninhibitorand 0.75% of Cm'saturated cyclo-alkyl allophanateas carbonmodifier was subjected to-a 36-hour test in .a Chevrolet test engineunder severe operating conditions (3150 R.'P. MJ. .At the end of thetest the engine parts were free from lacquer and carbon deposits. a

' 1. An improved lubricant comprising a mineral lubricating oil havingdissolved therein a small amount each of an oil-soluble detergentnormally,

tending to .promote scratching or scufling of pistons and an oil-solubleallophanate selected from the group cons sting of allophanates of.alicarbocyclic alcohols and thio-aicohols. having at least 12 carbonatoms.

- 2. An improved lubricant comprising mineral lubricating oil havingdissolved therein a relatively small amount each of an oil-solubledetergent normally tending to promote scratching or scufling of pistons.an amine anti-oxidant, and oil-soluble allophanate selected from thegroup consisting of allophanates of alicarbocyclic alcohols andthio-alcohols, having at least 12 carbonatoms. v 3.,An improvedlubricanocomprising a mineral lubricating oil having dissolved there n25% to 5% of an oil soluble detergent normally tending to promotescratching or scufling of-pistons and .1% to 10% of an oil-solubleallophanate'selected from the group consisting of allophanates ofalicarbocyclic alcohols and-thin-alcohols,-having at least 12 carbonatoms.

4. An improved lubricant comprising a mineral lubricating oil havingdissolved therein 25% to Y 16.5% of an oil-soluble detergent-normally'tendg promote scratching or scufling of pistons and :rom .5% to 5% ofan oil-soluble allophanate seected from the group consisting ofallophanates if alicarbocyclic alcohols and thici-alcohols, havng atleast 12 carbon atoms.

'5. An improved lubricant comprising a minaral lubricating oil havingdissolved therein 25% to 5% of an oil-soluble detergent normally tendingto promote scratching or sending of pistons, .1% to 1% of anamineanti-oxidant, and .1% to of an oil-soluble allophanate selectedfrom the group consisting of allophanates of alicarbocyclic alcohols andthio-alcohols, having at least 12 carbon atoms.

6. An improved lubricant comprising a mineral lubricating oil havingdissolved therein .25% to 5% of a polyvalent metal salt of petroleumsulfonate, and to 10% phanate selected from the allophanates ofalicarbocyclic alcohols and thioalcohols having at least 12 carbonatoms.

'7. An improved lubricant comprising a mineral lubricating oil havingdissolved therein to 5% calcium petroleum sulfonate, .1% to 1% phenylalpha naphthylamine, and .1% to 10% of a branched-chain alkyl decalolallophanate.

8. The combosition of claim 7 wherein said decalol has 18 carbon atoms.

9. The composition of claim 7 in which the viscos-itv index of themineral lubricating oil is above 50.

PAUL R. VAN ESS. ELLIS R. WHITE.

of an oil-soluble allo- I group consisting of

